Aromatic hydrocarbon inhibitor



United States Patent 3,342,723. AROMATIC HYDROCARBON INHIBITOR Richard L. Godar, St. Louis, Mo., assignor to Petrolite Corporation, Wilmington, Del., a corporation of Delaware No Drawing. Continuation of application S er. No.

129,511, Aug. 7, 1961. This application Aug. 25,

1965, Ser. No. 482,611

6 Claims. (Cl. 208-48) This application is a continuation of application Serial No. 129,511 filed on Aug. 7, 1961.

This invention relates to a method of chemically treating hydrocarbon liquids which contact surfaces under high temperature conditions in order to inhibit, prevent and/or reduce the deposition of substances thereon. More specifically, this invention relates to the chemical treatment of the metal surfaces in contact with petroleum hydrocarbon liquids under conditions of high temperatures whereby said liquids tend to form deposits on such metal surfaces. This invention also relates to compositions employed in these processes.

In the processing of hydrocarbon liquids particularly petroleum hydrocarbon liquids, elevated temperatures are often used in many necessary and important operations. To handle liquids at elevated temperatures, heat exchangers and the like devices are often employed to control the heat transfer rate from one operational step to another. When hydrocarbon liquids contact hot metal surfaces, there is sometimes a tendency for the liquid to decompose or undergo a chemical reaction that manifests itself in the form of deposits. These deposits may be either coke-like or they may be in the form of tenacious, soft, sticky sludges which adhere to hot surfaces. Adherence of deposits,- rather than deposit-formation itself is the essence of the problem, in contrast to fuel storage where residue in the oil itself creates the problem.

The problem is well recognized in the art-Note Petroleum Products Handbook, Guthrie (McGraw-Hill, 1960) pages 1-13, and elsewhere.

v These deposits tend to materially decrease the heat transfer capacities of the metal surfaces and hence irii crease operating expenses. These deposits also require additional effort and time to remove and to restore the equipment to its original operating efficiency.

Petroleum refinery operations often encounter the above described conditions inmany stages in the refining process;

These deposits form on heat transfer surfaces at temperatures as low as about 200-225 F. andmay be evidenced at temperatures as extreme as 800 F'.

It. is ,practictllly.. imposa blel p n these ep s ts. by coating the metal surfaces with a protective permanent.

coating due to the possible loss of heat transfer. In addition, the large volume of liquid that contacts such equipment increases the problem of treating metal surfaces in petroleum progessing to prevent high temperature deposits.

It would be advantageous if a chemical agent could be added in an extremely small amount to ahydrocarbon liquid which tends to form high temperature deposits whereby such deposits-would. be prevented. It would also.

be desirable if such a chemical would not only prevent such deposits but would also remove them without necessitating thefstoppage of a given operation. It therefore becomes an' object of the present invention to prevent the formation of high temperature deposits on metal surfaces by chemical means. 7 Another object is tofurnish a chemical which when added to a hydrocarbon liquid will prevent the depositforming tendenciesof sai d liquid when it contacts metal surfaces atfeleyated temperaturesd 1 3,342,723 Ce Patented Sept. 19, 1967 A further object is to provide a chemical treatment which will prevent the formation of high temperature deposits by petroleum hydrocarbon liquids in contact with heat transfer equipment.

Yet another object is to furnish a chemical treatment capable of being combined with a thermally unstable, deposit-forming liquid whereby said liquid will not form deposits upon metal surfaces at elevated temperatures.

Still another object is to provide a chemical treatment which will remove high temperature deposits from metal surfaces of petroleum refining equipment without the necessity of stopping the operations of such equipment. Other objects will appear hereinafter.

In accomplishing these objects in accordance with the invention it has been found that new and improved results in preventing, inhibiting and/ or reducing the formation of deposits from petroleum hydrocarbon liquids during the processing thereof at elevated temperatures, particularly at temperatures within the range of about 200- 225 F. to 800 F., are obtained by adding to, preferably by dissolving or dispersing in the hydrocarbon liquid, the antifouling agents of this invention.

The antifouling agents of this invention are ortho nuclear substituted aromatic compounds which contain two radicals selected from the group consisting of amino and phenolic radicals which are ortho substituted inter se on the aromatic nucleus. These compounds may also be substituted inter se on the aromatic nucleus. These compounds may also be substituted With other radicals. Thus, compounds of this invention may be represented as follows:

where Z represents the residue of the aromatic compound within other positions on the aromatic nucleus may be substituted or unsubstituted.

By way of example, monocyclic compounds of this invention may be represented by the following formulae where X and Y are amino or phenolic hydroxy groups and- R is' a substituted group, for example, a hydrocarbon 1 group such as alkyl, cycloalkyl, phenyl, etc. and n is an integer 0-3, for example OH I 9 Q-on ONE: ONE: 7

and the substituted derivatives thereof, preferably the nuclear substituted :alkyl or phenyl derivatives thereof, wherein the remaining positions on the aromatic nucleus may be substituted or unsubstituted, for example,

(I)H NH: NH: 7 i 4 alkyl y 3 ?11 NH: NH:

OH NH; OH

phenyl phenyl phenyl The condtions encountered in refinery operations are simulated by exposing petroleum products taken from various refineries to high temperature heat exchange tubes in the absence of and in the presence of the anti-fouling compositions of this invention.

A CPR fuel coker model OIFC is employed to simulate these conditions. It is described in CRC Manual No. 3, March 1957, published by the Coordinating Fuel and Equipment Research Committee of the Coordinating Research Council, Inc. The standard procedure is employed except that the equipment is modified so as to bypass the filter section.

The conditions of the test are as follows:

Test time, minutes 30 Test temperature, F. 575 Test pressure, p.s.i 250 Test rate of flow, lbs./hr 3 The amount of fouling which occurs is measured by observing the preheater (or heat exchanger) tube before and after the test to determine the amount of deposits formed on the preheater tube. One finds that the appearance of the preheater tube corresponds to the amount of fouling as measured by gravimetric means. Gravimetric resuits generally corroborate the results obtained by inspection of the tube. Thus, the terms employed in the following table have the following meaning:

Mg. Heavy fouling 812 Moderately heavy 6-8 Moderate fouling 4-6 Light fouling 2-4 Very light fouling under 2 mg.

TABLE I P.p.m Fouling Ex. Additive Em- Deposit on ployed Exchanger Tube 1 None Heavy.

2 Octyl resorcinol 10 Heavy.

OctylQOH 3- Eugenol. 100 Heavy.

HO- CH2-OH=CH2 4 Hydroquinone 25 Heavy.

5 2,6-ditert-butyl-4-methy1 phenol 25 Heavy.

OH (?H& $Ha CH (i1 C-CH CH3 CH3 TABLE I-Contlnued P.p.m. Fouling Ex. Additive Em- Deposit on ployed Exchanger Tube 6. Pyrogallol 25 Heavy.

HO- OH 7- 4-pheny1 eateehol 25 Light.

8. 4-tert-butyl catechol 25 Very light.

I Q-OH CHaC3 a 9 25 Heavy.

O H @011; CHa-(f-OH:

CHz-C H3 10. oPhenylene diamine 25 Light.

11 p-Phenylene diamine 25 Moderately heavy. NHr-O-NH:

12. o-Amlnopheuol 25 Moderate.

13. p-Amino phenol- 25 Heavy.

14. Oatechol 25 Light.

The above tests are typical of the screening tests employed in evaluating antifouling additives. After being screened in this manner, the antifouling additives are employed in petroleum refinery operations. By means of the above tests, the most effective additive is selected for the particular hydrocarbon under consideration and the additive is then employed in the specific operation.

The antifouling additive can be employed in refining crude petroleum as well as in the treatment of any component thereof which are exposed to high temperatures including the light distillates, for example light naphthas, intermediate naphthas, heavy naphthas, etc.; middle distillates, for example kerosene, gas oil, etc.; distillate lube oil stocks, for example, white oil, saturating oil, light lube oil, medium lube oil, heavy lube oil, and the like.

In addition, the additive can be employed with other hydrocarbons such as xylene, benzene, purified hydrocarbon compounds, etc. In addition, they can be employed under certain conditions with non-hydrocarbons, such as alcohols, phenols, etc. For example, they can be employed in a toluene extraction tower and stripper which process comprises mixing phenol and toluene in an extraction whereby phenol extracts impurities from toluene and the raffinate is subsequently removed. Thereafter the mixture is sent to a stripper where the toluene is removed from the phenol by distillation. The remaining phenol is recycled to the extractor for further use. The system is operated over a wide temperaure range for example 230-425 F. Deposits in the phenol circuit cause the loss of excessive amounts of phenol. It can be used in heat transfer units used in a furfurol extraction process processing for example, intermediate distillates, paraffin distillates, decanted oil, vacuum cylinder stock, deasphalted cylinder stock, etc.

The amount of antifouling agent required in this invention is subject to wide variation but in general very effective results have been obtained by adding relatively minute amounts of the antifouling agent to the hydrocarbon liquid being processed, for example, amounts may be as low as 0.5 p.p.m. in hydrocarbon liquid, for example 1 to 500 p.p.m. or higher, for example, 1000 or more p.p.m., preferably 5 to 50 p.p.m., with an optimum of 15- 30 p.p.m. In general, the upper limit is determined by the economics of the process but other factors should be taken into consideration such as whether large amounts will have any adverse effects on present or subsequent operations. Because of the many different types of operations where hydrocarbons are heated to elevated temperatures under conditions where deposits are formed, it is difficult to give specific ranges which will be effective in all operations. The amount of agent which inhibits the formation of deposits is referred to herein as an antifouling amount. The above figures relate to p.p.m. in terms of active antifouling chemical not including the solvent employed.

Inasmuch as the antifouling agent is employed in such small amounts and it is preferable to feed it continuously or semicontinuously by means of a proportioning pump or other suitable device to the particular hydrocarbon liquid being processed or to add them in a similar manner to the apparatus in which the hydrocarbon liquid is being processed, it is desirable to incorporate the agent or a mixture of agents into a suitable solvent which will be compatible with the liquid which is to be processed. The solvent which is used to dissolve the active ingredient is also subject to some variation depending upon the solubility characteristics of the particular compound employed. In some cases, even though the active mixture is insoluble in a particular solvent, it will dissolve in a combination of solvents.

In the practice of the invention it is very desirable to start the treatment with the chemicals employed for the purpose of the invention at a higher dosage, say 50 to 60 p.p.m. or more ,of a composition and then gradually reduce the dosage to the point where fouling of the apparatus is just eliminated or substantially reduced.

The invention is especially valuable where sour naphthas are being processed or where the oil being processed is a mixture containing some sour naphthas.

Examples of specific types of apparatus to which the chemical compositions of the invention can be added during petroleum processing are fractioning towers, stripping columns, debutanizers, depropanizers, deeth-anizers, heat exchangers, reboilers, hot product lines and other metal equipment (usually ferrous metal) which is brought into contact with the organic liquids being processed at relatively high temperatures. The invention makes it possible to extend the useful life of crude oil fractionating towers and other types of petroleum refinery equipment. It also makes it possible to provide cleaner inside surfaces resulting in better fractionation, better heat exchange in coolers, far less severe plugging and less time required for cleaning and maintenance.

Having thus described my invention what I claim as new and desire to obtain by Letters Patent is:

1. A process for inhibiting in oil refining apparatus during petroleum refining operations the formation of adherent coke-like deposits and adherent tenacious soft, sticky sludges on, and the adhesion of said deposits and sa1d sludges to, the hot metal heat transfer surfaces of a heat exchanger in said oil refining apparatus by a thermally unstable petroleum hydrocarbon liquid, said hydrocarbon liquid having the tendency to undergo a chemical reaction at a temperature in the range of about 225 F. to about 800 F., said chemical reaction manifesting itself in the form of adherent coke-like deposits and adherent soft, sticky sludges, such as are usually formed during passage of said hydrocarbon liquid through said heat exchanger and in contact with the hot metal surfaces of said heat exchanger in said oil refining apparatus at a temperature in the range of about 225 F. to about 800 F. comprising (1) incorporating in said hydrocarbon liquid prior to contact with said metal surfaces of said heat exchanger in said oil refining apparatus an antifouling amount of a compound selected from the group consisting of 4-phenyl catechol, 4-tert-butyl catechol, orthophenylene diamine, orthoaminophenol, and catechol, and

(2) heating said hydrocarbon liquid having incorporated therein said compound in an antifouling amount to a temperature in the range of about 225 F. to about 800 F. by contact with said hot metal surfaces of said heat exchanger in said oil refining apparatus.

2. The process of claim 1 where the compound is 4- phenyl catechol.

3. The process of claim 1 where the compound is 4-tertbutyl catechol.

4. The process of claim 1 where the compound is orthophenylene diamine.

5. The process of claim 1 where the compound is orthoamino phenol.

6. The process of claim 1 where the compound is catechol.

References Cited UNITED STATES PATENTS 2,063,212 12/1936 Wilson 252-40 3 2,084,754 6/1937 Wilson 252-403 2,181,102 11/1939 Stoesser et a1. 260-620 2,354,252 7/1944 Fraser et a1. 252403 2,892,785 6/1959 Harle et a1 252-403 LEON D. ROSDOL, Primary Examiner.

ALBERT T. MEYERS, Examiner.

I. FEDIGAN, Assistant Examiner. 

1. A PROCESS FOR INHIBITING IN OIL REFINING APPARATUS DURING PETROLEUM REFINING OPERATIONS THE FORMATION OF ADHERENT COKE-LIKE DEPOSITS AND ADHERENT TENACIOUS SOFT, STICKY SLUDGES ON, AND THE ADHESION OF SAID DEPOSITS AND SAID SLUDGES TO, THE HOT METAL HEAT TRANSFER SURFACES OF A HEAT EXCHANGER IN SAID OIL REFINING APPARATUS BY A THERMALLY UNSTABLE PETROLEUM HYDROCARBON LIQUID, SAID HYDROCARBON LIQUID HAVING THE TENDENCY TO UNDERGO A CHEMICAL REACTION AT A TEMPERATURE IN THE RANGE OF ABOUT 225*F. TO ABOUT 800*F., SAID CHEMICAL REACTION MANIFESTING ITSELF IN THE FORM OF ADHERENT COKE-LIKE DEPOSITS AND ADHERENT SOFT, STICKY SLUDGES, SUCH AS ARE USUALLY FORMED DURING PASSAGE OF SAID HYDROCARBON LIQUID THROUGH SAID HEAT EXCHANGER AND IN CONTACT WITH THE HOT METAL SURFACES OF SAID HEAT EXCHANGER IN SAID OIL REFINING APPARATUS AT A TEMPERATURE IN THE RANGE OF ABOUT 225*F. TO ABOUT 800*F. COMPRISING (1) INCORPORATING IN SAID HYDROCARBON LIQUID PRIOR TO CONTACT WITH SAID METAL SURFACES OF SAID HEAT EXCHANGER IN SAID OIL REFINING APPARATUS AN ANTIFOULING AMOUNT OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF 4-PHENYL CATECHOL, 4-TERT-BUTYL CATECHOL, ORTHOPHENYLENE DIAMINE, ORTHOAMINOPHENOL, AND CATECHOL, AND (2) HEATING SAID HYDROCARBON LIQUID HAVING INCORPORATED THEREIN SAID COMPOUND IN AN ANTIFOULING AMOUNT TO A TEMPERATURE IN THE RANGE OF ABOUT 255*F. TO ABOUT 800*F. BY CONTACT WITH SAID HOT METAL SURFACES OF SAID HEAT EXCHANGER IN SAID OIL REFINING APPARATUS. 